There is a few differences, the P Plus has the Fender Lace Sensor pick ups and a 22 fret neck. The body is also quite different in shape, it has a top horn shaped like a "Boner" hence its nick name. Fender only built them for a few years. I must admit I dont know the technical stuff about it in detail. I bought it when I was about 15 and have played it ever since, its the only bass I have ever owned but I plan to but a cheaper bass to use for gigs in pubs etc.
Love the classic look.